- Seen in a classic bimodal age distribution—the primary peak in children aged 5–15 years (most common pediatricnonglial suprasellar neoplasm) and a second peak in adults aged 50–70 years—presenting with visual field defects (bitemporal hemianopia), growth failure/short stature, diabetes insipidus, and obstructive hydrocephalus from third ventricular compression.
- Caused by a benign (WHO Grade 1) epithelial neoplasm arising from squamous epithelial remnants of Rathke's pouch along the pituitary stalk (infundibulum) and tuber cinereum:
- 1.**Adamantinomatous Subtype (Pediatric Peak, CTNNB1 / β-catenin mutation): Lobulated calcified (90%), multicystic suprasellar mass containing cholesterol-rich 'crankcase / machine-oil' fluid** and wet keratin nodules; locally adherent to the hypothalamus and optic apparatus.
- 2.**Papillary Subtype (Adult Peak, BRAF V600E mutation): Predominantly solid or monocystic spherical suprasellar/third ventricular mass** lacking calcification and lacking machine-oil T1-bright fluid.
Imaging Findings
- MRI Brain & Sella Protocol (Anatomical, Hypothalamic & Chiasmatic Gold Standard):
- –Suprasellar Epicentre: Centered in the suprasellar cistern (75% combined suprasellar/intrasellar, 20% purely suprasellar), with the normal pituitary gland often identifiable separately at the floor of a normal-sized sella.
- –T1WI ('Machine-Oil' Cysts): Adamantinomatous cysts show marked intrinsic T1 hyperintensity due to high protein, cholesterol crystals, and methemoglobin.
- –T2WI / FLAIR: Hyperintense cystic components with heterogeneous solid nodules; surrounding FLAIR hyperintensity in the optic tracts and hypothalamus ('edema along the optic tracts') is a classic diagnostic clue.
- –T1 C+ (Contrast): Vivid peripheral cyst-wall enhancement and heterogeneous enhancement of solid mural nodules.
- –DWI / ADC: Typically demonstrates facilitated diffusion (no diffusion restriction) within both the cystic and solid components, distinguishing it from intrasellar/suprasellar epidermoid cyst (which restricts avidly on DWI).
- –**SWI / T2* GRE: Demonstrates prominent eggshell/rim and nodular blooming artifact** corresponding to the coarse calcifications present in 90% of adamantinomatous tumours.
- CT & Plain Skull Radiograph (X-Ray) Findings:
- –Non-Contrast CT Head ('Rule of 90%'): Complementary to MRI because CT definitively demonstrates coarse, curvilineal/eggshell and nodular suprasellar calcifications (~90% of pediatric cases) and low-attenuation cysts (~90%).
- –Lateral Skull X-Ray: Classic flocculent or curvilinear suprasellar calcification above the sella turcica with erosion/flattening of the dorsum sellae and clinoid processes.
Differential Diagnosis
| Differential Diagnosis | Key Distinguishing Features |
|---|---|
Pituitary Macroadenoma | Rare in young children; centered in a ballooned sella turcica ('snowman' shape), normal pituitary gland not separately visible, and calcification is rare (<2%). |
Rathke Cleft Cyst | Simple non-calcified midline cyst between the anterior and posterior pituitary lobes containing a non-enhancing intracystic T2-dark mucinous nodule, with no solid nodular enhancement. |
Suprasellar Epidermoid Cyst | Insinuating CSF-like mass that avidly restricts on DWI, lacks contrast enhancement, and rarely calcifies. |
Hypothalamic / Optic Chiasm Pilocytic Astrocytoma | Enlarges the optic chiasm/hypothalamus itself (often in NF1), shows a cyst with an intensely enhancing mural nodule, and rarely calcifies. |
Important Points to Remember
- Combined MRI + Non-Contrast CT Protocol: Always pair Pituitary MRI with a thin-slice Non-Contrast CT to confirm suprasellar calcifications and map bony sphenoid anatomy prior to transsphenoidal or transcranial surgery.
- Hypothalamic-Sparing Strategy & BRAF Targeted Therapy: Because aggressive resection of hypothalamic-adherent adamantinomatous craniopharyngioma causes severe hypothalamic obesity and panhypopituitarism, modern UK multidisciplinary practice favours hypothalamic-sparing subtotal resection + conformal radiotherapy (or proton beam therapy); in adult papillary craniopharyngiomas, BRAF V600E inhibitors produce dramatic tumour shrinkage.